1. Field of the Invention
This invention relates, in general, to closures and more particularly to closures having an expanded peripheral surface, and methods for their use and manufacture.
2. Description of Related Art
The past number of years has seen a substantial growth in distinctive food packaging designs intended to promote brand identity, product distinction and consumer convenience. One market segment of particular emphasis is that of relatively small “single service” packages of consumable fluids such as dairy and juice products. The nature of these products justifies the “value added” appeal of such distinctive packaging.
Often the unique “single service” packaging involves design features on both a container and closure. Regarding closures, it is often advantageous to have a relatively large, expanded outside diameter region for ease of gripping and/or aesthetic appearance combined with a smaller diameter cylindrical skirt on which a container engagement structure such as threads is disposed. The smaller diameter skirt is intended to mate with a container neck of diameter suitable for ease of pouring or drinking while the expanded outside diameter improves manual handling of the closure.
One way to achieve a desired relationship between outside diameter and inside diameter would be to form a solid cylinder closed at one end. However, in many cases the thickness of the cylindrical shape would be excessive, leading to impractical processing requirements and excessive material consumption. Thus, one approach to achieving an expanded outside “gripping” diameter for a closure is the design of a “double shell” arrangement for the closure, such as that embodied in U.S. Pat. No. 6,783,014 to Luker. In this “double shell” arrangement, an inside skirt and an outside skirt both depend from a common, typically disk-like top. The inside skirt normally includes container engaging structure while the outside skirt offers improved handling characteristics. An annular space separates inside and outside skirts.
Another arrangement to achieve an expended outside gripping surface combined with a reduced diameter neck engaging structure is shown in U.S. Pat. Nos. 5,853,097 and 5,967,351 to Ekkert, and in U.S. Pat. Nos. 5,950,849 and Des. 408,284 to Ekkert et al. In the Ekkert patents there is shown a closure design having a top wall in the form of a circular disk defining an outermost diameter. A skirt having a diameter less than the outermost diameter of the top wall depends from the top wall. The depending skirt includes threads positioned on its cylindrical inner wall to mate with complimentary container threads. A plurality of arcuately shaped parallel ribs extends from the bottom surface of the top wall to the exterior surface of the depending skirt. The combination of the top wall diameter extension and the parallel ribs forms an enlarged grasping area for manual handling of the closure.
A number of issues arise when reviewing the overall features of the closures embodied in the above-mentioned Ekkert patents. First, to facilitate application of the closure to the container, the tamper evident band is shown and taught to be spaced outwardly from the closure skirt. This arrangement, when combined with the extending solid top surface, creates a circumferential pocket wherein the mold steel forming the ribs is disposed during manufacture. Thus, this arrangement requires the mold to incorporate components commonly referred to as “slides”, which remove the rib forming metal in a direction essentially perpendicular to the closure axis. This of course complicates molding and cost. Moreover, this arrangement forces the ribs to be disposed in aesthetically restricted parallel positioning. Finally, the arrangement is accompanied by detailed tapering of the ribbing as is described in the above-mentioned Ekkert '097 patent.
A second issue associated with the closures embodied in the Ekkert patents is the interference type mechanism of the tamper evident band. This type of band has proven to be somewhat unreliable when the closure is used in conjunction with containers produced by relatively imprecise manufacturing such as extrusion blow molding.
A third issue associated with the embodiments of the Ekkert patents is the integral joining of the ribs to both the underside of the top wall extension and the outer surface of the inner depending skirt. This structural situation is essentially present in many prior art disclosures. Further examples are taught in U.S. Design Pat. Nos. 369,748, 370,631, 371,074 to Zemlo et al., U.S. Design Pat. No. 405,695 to Zemlo, and U.S. Design Pat. No. 409,491 to Ullrich et al. These patents all show ribs extending between and joined to both the top surface and inner skirt of the closure. This structural arrangement causes the skirt to be relatively rigid and unyielding. The result is that the threads may need to be formed by a rotating tool component which essentially unscrews to remove the component from the closure during part ejection from the mold. This significantly increases the complexity of the mold compared to ejection using straight axial movement only. In addition, this objectionable aspect is normally accompanied by an increase in material consumption for the part.
It is noted that some embodiments of the Ekkert disclosure identified above involve removal of the top wall extension such that the ribs are freestanding. Specifically, the embodiments of FIG. 9 of the Ekkert '849 patent and FIGS. 11 and 12 of the Ekkert '097 patent show no extension of the top surface radially outward of the closure skirt dimension. In these cases, the mold and manufacturing complexities defined above could be alleviated. However, these suggestions bring about other problems. First, the large open exposed regions between ribs are aesthetically objectionable. Second, in order for the unsupported ribs to function properly they would likely have to be thickened to prevent bending and distortion during application and consumer handling. Finally, a significant amount of valuable label area on the top surface of the closure is lost using these embodiments.
There is thus a continuing need for improved closures having an expanded diameter gripping surface along with a reduced diameter container engagement structure from the perspectives of aesthetics, material consumption, performance and manufacturability.